The next generation mobile wireless communication system, which is referred to as Third Generation Partnership Project (3GPP) Fifth Generation (5G) or New Radio (NR), will support a diverse set of use cases and a diverse set of deployment scenarios. The latter includes deployment at both low frequencies in the range of hundreds of megahertz (MHz), similar to Long Term Evolution (LTE) today, and very high frequencies referred to as millimeter wave (mmW) in the range of tens of gigahertz (GHz).
Similar to LTE, NR will use Orthogonal Frequency Division Multiplexing (OFDM) in the downlink from a NR base station (gNB) to a User Equipment device (UE). In the uplink from the UE to the gNB, both Discrete Fourier Transform (DFT) spread OFDM and OFDM will be supported.
The basic NR physical resource can thus be seen as a time-frequency grid as illustrated in FIG. 1, where each Resource Element (RE) corresponds to one OFDM subcarrier during one OFDM symbol interval. Resource allocation in a slot is described in terms of Resource Blocks (RBs) in the frequency domain and number of OFDM symbols in the time domain. A RB corresponds to 12 contiguous subcarriers and a slot consists of 14 OFDM symbols.
Different subcarrier spacing values are supported in NR. The supported subcarrier spacing values, which are also referred to as numerologies, in NR are given by Δf=(15×2α) kHz where α is a non-negative integer.
In the time domain, downlink and uplink transmissions in NR are organized into equally-sized subframes similar to LTE as shown in FIG. 2. A subframe is further divided into slots and the number of slots per subframe is 2α+1 for a numerology of (15×2α) kHz.
NR supports “slot based” transmission. In each slot, the gNB transmits Downlink Control Information (DCI) about which UE data is to be transmitted to and what resources in the current downlink subframe the data is transmitted on. The DCI is carried on the Physical Downlink Control Channel (PDCCH) and data is carried on the Physical Downlink Shared Channel (PDSCH).
This PDCCH is typically transmitted in Control Resource Sets (CORSETs) in the first few OFDM symbols in each slot. A UE first decodes PDCCH and if a PDCCH is decoded successfully, it then decodes the corresponding PDSCH based on the decoded DCI in the PDCCH.
Uplink data transmissions are also dynamically scheduled using PDCCH. Similar to downlink, a UE first decodes an uplink grant in a DCI carried by PDCCH and then transmits data over the Physical Uplink Shared Channel (PUSCH) based on the decoded control information in the uplink grant such as modulation order, coding rate, uplink resource allocation, etc. Each UE is assigned a unique Cell Radio Network Temporary Identifier (C-RNTI) during network connection. The Cyclic Redundancy Check (CRC) bits attached to a DCI for a UE are scrambled by the UE's C-RNTI, so a UE recognizes its own DCI by checking the CRC bits of the DCI against the assigned C-RNTI.